Advancement Techniques For Gastrointestinal Tool With Guiding Element

ABSTRACT

Gastrointestinal apparatus ( 200 ) is provided for use with a fluid pressure source ( 240 ). The gastrointestinal apparatus ( 200 ) includes a guiding element ( 214 ), adapted to be inserted into a colon, and a piston head ( 220 ) coupled to a distal portion of the guiding element ( 214 ). The piston head ( 220 ) is adapted to be inflated to form a first pressure seal between the piston head ( 220 ) and a wall of the colon after the guiding element ( 214 ) has been inserted into the colon, and be advanced distally through the colon in response to pressure from the fluid pressure source ( 240 ) applied to an external surface of the piston head ( 220 ). The apparatus ( 200 ) further includes a gastrointestinal tool ( 210 ) adapted to be advanced along the guiding element ( 214 ), and an annular balloon ( 228 ) coupled around a distal portion of the gastrointestinal tool ( 210 ), the balloon ( 228 ) expandable to form a second pressure seal between the distal portion of the gastrointestinal tool ( 210 ) and the wall of the colon. Other embodiments are also described.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication 60/652,049, filed Feb. 10, 2005, which is assigned to theassignee of the present application and is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates generally to gastrointestinal tools, such asendoscopes and colonoscopes, and more particularly to gastrointestinaltools that slide over a guidewire, guiding catheter and the like, andwhich may be introduced into and through the colon, e.g., to the cecum,by any means.

BACKGROUND OF THE INVENTION

Endoscopy has become an increasingly important tool in diagnosing and intreating ailments of the gastrointestinal tract, also referred to as theGI tract. Typical endoscopes are essentially formed by a somewhatflexible tube that is pushed through the GI tract, after beingintroduced in the body cavity starting from the rectum or starting fromthe esophagus. The endoscope has a steerable tip to facilitatenavigation through the GI tract, and typically has to be sufficientlystiff so that it can be pushed further along the body cavity. The tip ofthe endoscope that is introduced in the GI tract can be outfitted withseveral devices, most notably an illumination device and a visiondevice, such as a vision integrated circuit, so that the operator of theendoscope can observe the interior of the GI tract and maneuver theendoscope in the proper position.

Once the endoscope is in position, other tools attached to the endoscopeor inserted through the endoscope can be brought to the proper positionin the GI tract. Various procedures can then be carried out, such asremoving polyps, performing sutures, irrigation, suction, and removingother tissues. The various tools that are used together with theendoscope can be either inserted separately in the GI tract and placedin the proper position independently, or may travel in a working channelof the endoscope, so that once the endoscope is positioned at thedesired location in the GI tract, the tools inserted in the endoscopewill also easily reach that position.

Endoscopes or other smaller similar devices can also be used to exploreother body cavities, for example airways, genitourinary tract, femalereproductive organs, etc., or blood vessels. These probes must be smallto fit in the smaller cavities, and care must be taken to avoid damageto the more fragile membranes lining these cavities.

Current state of the art endoscopes are very capable devices, andendoscopy has been very successful in diagnostic and therapeuticapplications with the use of current endoscopes and the current arsenalof tools that can be inserted through the working channel of theendoscope, or can be attached to the outside of the endoscope. However,current endoscope technology has limitations and drawbacks. One of thegreatest drawbacks of current endoscopes is that the working channel issmall. The working channel is small relative to overall diameter of theendoscope, and is further limited by the space taken up by vision,irrigation, suction, light, and control cabling mechanisms that are partof the endoscope and are required to control the endoscope. Thus thereis a very small area left for other tools to be introduced through theendoscope. Also, the additional channels may make passage of theendoscope through body cavities more difficult, as they contribute amongother things to its diameter.

U.S. Patent Application Publication 2005/0038318 to Goldwasser, which isassigned to the assignee of the present application and is incorporatedherein by reference, describes gastrointestinal apparatus including aguidewire, and a gastrointestinal tool formed with a bore, the guidewirepassing through the bore. For some applications, the gastrointestinalapparatus includes an inflatable device, adapted to pull the guidewirethrough a colon of a subject.

U.S. Pat. No. 6,517,477 to Wendlandt, assigned to Scimed Life Systems,Inc. (Maple Grove, Minn., U.S.), which is incorporated herein byreference, describes a catheter introducer system for endoscopy thatincludes a steering section and a propulsion section located near theend of the flexible, tubular catheter that is introduced in a bodycavity. The propulsion section is designed to pull the rest of thecatheter inside the body cavity, so there is no need to push thecatheter along from outside the body. Propulsion may be accomplished byrelatively movable gripping pads that selectively apply suction to thetissue. The steering section is designed to point the end of thecatheter that is introduced into the body cavity in the desireddirection. The catheter may be made very flexible in bending, and alarger diameter catheter may be used.

U.S. Pat. No. 6,800,056 to Tartaglia et al., which is incorporatedherein by reference, describes an endoscope with guiding apparatus. Asteerable endoscope is described having an elongate body with a manuallyor selectively steerable distal portion, an automatically controlledportion, a flexible and passively manipulated proximal portion, and anexternally controlled and manipulatable tracking rod or guide. Thetracking rod or guide is positioned within a guide channel within theendoscope and slides relative to the endoscope. When the guide is in aflexible state, it can conform to a curve or path defined by thesteerable distal portion and the automatically controlled portion. Theguide can then be selectively rigidized to assume that curve or path.Once set, the endoscope can be advanced over the rigidized guide in amonorail or “piggy-back” fashion so that the flexible proximal portionfollows the curve held by the guide until the endoscope reaches a nextpoint of curvature within a body lumen.

U.S. Patent Application Publication 2004/0199087 to Swain et al., whichis incorporated herein by reference, describes a method for insertingguide wires into a lumen, for example into the human gastrointestinaltract. A guide wire structure is employed which comprises at least twoguide wires each having a leading end portion which terminates in aleading end, the guide wires being connected to one another by ajunction at or adjacent their leading ends, the guide wires have a firstposition in which the leading end portions are substantially parallel toone another, a second position in which the leading end portions arecurved, and a third position in which at least one of the leading endportions forms a loop. The guide wire structure is steered through thegastrointestinal tract by selectively advancing or retracting a singleguide wire or advancing more than one guide wire simultaneously,according to the path which is required to be followed.

U.S. Patent Application Publication 2004/0199088 to Bakos et al., whichis incorporated herein by reference, describes a guide wire including acontinuous, unitary wire having a first segment, a second segment, and athird segment. The third segment has a bending moment of inertia lessthan the bending moment of inertia of the first and second segments. Theguide wire is described as being used to advance a medical device withina body lumen.

PCT Patent Publication WO 2004/010858 to Gross et al., which isincorporated herein by reference, describes an imaging system comprisingan imaging device assembled on a carrier, and a first outwardlyexpandable element and a second outwardly expandable element mounted onthe carrier, wherein the second expandable element is expandable bothradially and axially, the imaging system comprising a mode of operation,wherein during expansion of the second expandable element, obstructionof the radial expansion of the second expandable element causes theaxial expansion of the second expandable element to propel the carrierand the imaging device axially.

PCT Publication WO 99/40957 to Blume et al., which is incorporatedherein by reference, describes a guide wire combined with a catheter ormedical device for moving through a body lumen to a desired position inthe body with the aid of an applied magnetic field. The guide wire isprovided with a magnet on its distal end that is oriented or orientedand moved by the application of a magnetic field to the magnet. Acatheter or other medical device is advanced over the guide wire. Oncethe medical device is in its desired position, the magnet may bewithdrawn through the lumen of the catheter.

U.S. Pat. No. 6,837,846 to Jaffe et al., which is incorporated herein byreference, describes an endoscope that is slidably insertable within alumen of a guide tube. The guide tube is configured to be rigidizablealong its entire length from a relaxed configuration. The endoscope hasa steerable distal portion to facilitate the steering of the devicethrough tortuous paths. In the relaxed configuration, a portion of theguide tube is able to assume the shape or curve defined by thecontrollable distal portion of the endoscope. Having assumed the shapeor curve of the endoscope, the guide tube may be rigidized by thephysician or surgeon to maintain that shape or curve while the endoscopeis advanced distally through the tortuous path without having to placeany undue pressure against the tissue walls.

U.S. Pat. No. 6,827,718 to Hutchins et al., which is incorporated hereinby reference, describes a steerable endoscope that uses rapid exchangetechnology, soft locks, and mechanical locks to maintain the position ofthe endoscope. Rapid exchange technology is used to minimizedisplacement forces present on the guidewire or catheters. Soft locksand mechanical locks are described as resisting movements caused bydisplacement forces.

U.S. Pat. No. 6,786,864 to Matsuura et al., which is incorporated hereinby reference, describes an endoscope including a fixing memberdetachably mounted to a distal end portion of an endoscope insertionpart for detachably fixing and holding a distal end portion of anindwelling tube or a distal end portion of a guide member for guidingthe indwelling tube, both of which are provided along the axialdirection of the insertion part, to the distal end portion of theinsertion part.

U.S. Pat. No. 6,695,771 to Takada, which is incorporated herein byreference, describes a self-propelled colonoscope that is self-insertedinto a colon by driving endless belts mounted on the outside of abending section of an insertion tube. The cross section of the endlessbelt is substantially circular, and rack gear teeth having a circularcross section are formed on the outside of the endless belts.

U.S. Pat. No. 6,764,441 to Chiel et al., which is incorporated herein byreference, describes a self-propelled endoscope including expandableactuators surrounding a central conduit. Each actuator comprises abladder that, when fluid is introduced, expands laterally whilecontracting longitudinally. A restorative spring can be placed inside abladder and between the two ends to restore the actuator to its originalshape as fluid is withdrawn. Multiple actuators can be placed in seriesto successively inflate and deflate and generate a peristaltic motion.One or more Shape Memory Alloy (SMA) springs can be affixed to one ormore restorative springs to cause bending motion.

U.S. Pat. No. 6,702,734 to Kim et al., which is incorporated herein byreference, describes a self-propelled endoscopic micro-robot that ispropelled through a tubular organ in forward and backward directions byan impact force generated within the robot by a propulsion piston thatis moved within a cylinder of the robot by an alternating source ofpressurized air.

U.S. Patent Application 2004/0199087 to Swain et al., which isincorporated herein by reference, describes a guide wire structure thatcomprises at least two guide wires each having a leading end portionwhich terminates in a leading end, the guide wires being connected toone another by a junction at or adjacent their leading ends, the guidewires have a first position in which the leading end portions aresubstantially parallel to one another, a second position in which theleading end portions are curved, and a third position in which at leastone of the leading end portions forms a loop. The guide wire structureis steered through the gastrointestinal tract by selectively advancingor retracting a single guide wire or advancing more than one guide wiresimultaneously, according to the path which is required to be followed.

The following patents and patent application publications, all of whichare incorporated herein by reference, may be of interest:

-   U.S. Pat. No. 4,176,662 to Frazer-   U.S. Pat. No. 4,148,307 to Utsugi-   U.S. Pat. No. 5,906,591 to Dario et al.-   U.S. Pat. No. 6,007,482 to Madni et al.-   U.S. Pat. No. 6,702,735 to Kelly-   U.S. Pat. No. 5,662,587 to Grundfest et al.-   U.S. Pat. No. 4,690,131 to Lyddy, Jr. et al.-   U.S. Patent Applications 2003/0225433 and 2003/0074015 to Nakao-   U.S. Patent Application 2004/0199196 to Ravo-   U.S. Patent Application 2004/0260150 to Bernstein-   U.S. Patent Application 2004/0204702 to Ziegler et al.-   U.S. Pat. No. 5,353,807 to DeMarco-   U.S. Pat. No. 5,740,808 to Panescu et al.-   U.S. Pat. No. 6,296,608 to Daniels et al.-   U.S. Pat. No. 4,040,413 to Ohshiro-   U.S. Pat. No. 4,561,427 to Takada

SUMMARY OF THE INVENTION

In some embodiments of the present invention, gastrointestinal apparatusis provided comprising an elongate guiding element; a mechanical device,adapted to pull the guiding element through a colon of a patient; and agastrointestinal tool adapted to advance along the guiding element. Forsome applications, the tool is shaped so as to define a boretherethrough, and the guiding element is placed within the bore. Forother applications, the tool comprises a coupling member shaped todefine a bore therethrough, a portion of which coupling member istypically positioned adjacent (e.g., laterally adjacent) to the tool. Asthe tool advances, successive portions of the guiding element aresurrounded by the bore. In an embodiment, the coupling member isintegral to the body of the tool. In another embodiment, the couplingmember is attached to the tool.

The term “guiding element,” as used in the specification and in theclaims, encompasses any elongate element adapted to be introduced into abody lumen in order to facilitate the advancement of another element(such as a gastrointestinal tool, e.g., a colonoscope) into the bodylumen, the guiding element including, but not limited to, such elementsas a guidewire, a guiding catheter, a monorail, or a wire, which may ormay not be hollow, and may or may not have segments, and may have anysuitable material property (e.g., flexible, metallic, non-metallic). Forsome applications, the guiding element comprises a plastic tube, e.g., aplastic tube having a diameter of between about 4 mm and about 6 mm,such as about 5.5 mm. For some applications, when the guiding elementcomprises a monorail, the monorail is flexible such that it generallydoes not reshape the colon.

In some embodiments of the present invention, the gastrointestinal toolis adapted to be passively advanced along the guiding element, such asby being pushed by the physician. Alternatively, the tool is adapted tobe actively advanced along the guiding element, such as by using anelectrical element. For example, the tool may comprise a spinning gear,adapted to rotate while grasping the guiding element, thereby propellingthe tool along the guiding element. For some applications, such aspinning gear is pneumatically or hydraulically powered.

In accordance with some embodiments of the present invention, theguiding element comprises a distal stop that prevents movement of thegastrointestinal tool therepast. Alternatively, for some applications,the guiding element does not comprise a distal stop. Further inaccordance with some embodiments of the present invention, thegastrointestinal tool comprises an imaging device, such as but notlimited to, a CCD camera, an illumination device, a vision device, anultrasound sensor, and/or an x-ray emitter. Additionally oralternatively, the gastrointestinal tool comprises a cutting tool, asampling device, and/or a magnetic device.

Still further in accordance with some embodiments of the presentinvention, the gastrointestinal tool comprises a catheter that advancesalong (e.g., over or alongside, as described above) the guiding element.For some applications, the catheter comprises a lumen for passingtherethrough at least one of an instrument and a fluid. In accordancewith an embodiment of the present invention, the gastrointestinal toolis shaped so as define a chamfer for facilitating passage through alumen.

There is also provided, in accordance with some embodiments of thepresent invention, a method for constructing a gastrointestinalapparatus, comprising providing a guiding element, providing amechanical device adapted to pull the guiding element through a colon ofa patient, and providing a gastrointestinal tool adapted to pass alongthe guiding element. In addition, for some applications, another tool isprovided that cooperates with the gastrointestinal tool, and is alsoadapted to be advanced along the guiding element. As anotheralternative, for some applications, a collapsible sleeve is adapted tobe slid over the guiding element and inflated to functionally create anendoscope with single or multiple channels that run through its length.

There is thus provided, in accordance with an embodiment of the presentinvention, gastrointestinal apparatus including a guiding element, and agastrointestinal tool including a coupling member formed with a bore,the guiding element passing through the bore. The gastrointestinalapparatus may include one or more of the following features. Forexample, the coupling member may be positioned inwards or outwards of anouter contour of the gastrointestinal tool. The gastrointestinal toolmay include a radioactive device (e.g., at least one of a radioactivetube, radioactive needle, radioactive seed, and radioactive capsule), aniontophoresis drug delivery device, an injection device for injection ofa substance, a photodynamic therapy/diagnosis device, a hyperthermictherapy/diagnosis device, an ultrasonic therapy/diagnosis device, and/oran imaging device.

A propulsion device may be adapted to propel the gastrointestinal toolalong the guiding element. An anchoring device (e.g., an inflatableballoon) may be adapted to anchor the guiding element at a position inthe gastrointestinal tract. Additionally or alternatively, thegastrointestinal tool may be coupled to a pulley.

There is therefore provided, in accordance with an embodiment of thepresent invention, gastrointestinal apparatus for use with a fluidpressure source, the gastrointestinal apparatus including:

a guiding element, adapted to be inserted into a colon;

a piston head coupled to a distal portion of the guiding element andadapted to:

-   -   be inflated to form a first pressure seal between the piston        head and a wall of the colon after the guiding element has been        inserted into the colon, and    -   be advanced distally through the colon in response to pressure        from the fluid pressure source applied to an external surface of        the piston head;

a gastrointestinal tool adapted to be advanced along the guidingelement; and

an annular balloon coupled around a distal portion of thegastrointestinal tool, the balloon expandable to form a second pressureseal between the distal portion of the gastrointestinal tool and thewall of the colon.

For some applications, the gastrointestinal tool is adapted to beadvanced along the guiding element when the annular balloon has been atleast partially deflated.

In an embodiment, the gastrointestinal tool is shaped so as to define achannel therethrough, and the guiding element is shaped to pass throughthe channel. Alternatively, the gastrointestinal tool includes acoupling member shaped so as to define a bore therethrough, and theguiding element is configured to pass through the bore and not to passthrough the gastrointestinal tool.

In an embodiment, the apparatus includes a passageway having proximaland distal ends, the proximal end coupled to the fluid pressure source,and the distal end open to a site between the external surface of thepiston head and the annular balloon.

In an embodiment, the gastrointestinal tool is shaped so as to define apassageway therethrough having proximal and distal ends, the proximalend coupled to the fluid pressure source, and the distal end open to asite between the external surface of the piston head and the balloon.

For some applications, the apparatus includes a vent tube, adapted tofacilitate passage of fluid out of the colon from a site distal to thepiston head.

There is further provided, in accordance with an embodiment of thepresent invention, gastrointestinal apparatus for use with an endoscopeshaped so as to define a channel therethrough, the gastrointestinalapparatus including:

a fluid pressure source; and

a piston head adapted to be coupled to a distal portion of theendoscope, the piston head adapted to:

be inflated so as to form a piston pressure seal between the distalportion of the endoscope and a wall of a colon when the endoscope is inthe colon, and

be advanced distally through the colon in response to pressure from thefluid pressure source applied to an external surface of the piston head.

For some applications, the apparatus includes a guide member, adaptedto: be at least partially insertable into a rectum, permit slidingmovement of the endoscope through the guide member, and create a rectalpressure seal between the guide member and the rectum.

For some applications, the apparatus includes a second fluid pressuresource, in fluid communication with an interior of the piston head viathe channel. For some applications, the apparatus includes a vent tube,adapted to facilitate passage of fluid out of the colon from a sitedistal to the piston head.

There is yet further provided, in accordance with an embodiment of thepresent invention, gastrointestinal apparatus for use with an endoscopeshaped so as to define a channel therethrough, the gastrointestinalapparatus including:

first and second fluid pressure sources; and

a piston head adapted to be coupled to a distal portion of theendoscope, the piston head adapted to be:

inflated to form a piston pressure seal between the distal portion ofthe endoscope and a wall of a colon when the endoscope is in the colon,

advanced distally through the colon in response to pressure from thefirst fluid pressure source applied to an external surface of the pistonhead,

coupled to the channel while the piston head is advanced through thecolon, such that the piston head is inflated by pressure from the secondfluid pressure source transmitted via the channel, and

decouplable from the channel, while in the colon, after the piston headhas been advanced through the colon.

For some applications, the piston head is adapted to be decoupled fromthe channel in response to one or more bursts of high pressure appliedto the channel.

For some applications, the apparatus includes a guide member, adaptedto: be at least partially insertable into a rectum, permit slidingmovement of the endoscope through the guide member, and create a rectalpressure seal between the guide member and the rectum.

For some applications, the apparatus includes a vent tube, adapted tofacilitate passage of fluid out of the colon from a site distal to thepiston head.

There is still further provided, in accordance with an embodiment of thepresent invention, a method including:

inserting a guiding element into a colon;

inflating a piston head coupled to a distal portion of the guidingelement, to form a first pressure seal between the piston head and awall of the colon after the guiding element has been inserted into thecolon;

inflating an annular balloon coupled around a distal portion of agastrointestinal tool, to form a second pressure seal between the distalportion of the gastrointestinal tool and the wall of the colon;

advancing the guiding element distally through the colon by applyingpressure to an external surface of the piston head; and

advancing the gastrointestinal tool along the guiding element.

In an embodiment, advancing the guiding element and advancing thegastrointestinal tool along the guiding element include alternatinglyadvancing the guiding element and the gastrointestinal tool along theguiding element until the gastrointestinal tool is advanced to a desiredsite in the colon.

There is also provided, in accordance with an embodiment of the presentinvention, a method including:

inserting, into a colon, an endoscope shaped so as to define a channeltherethrough;

inflating a piston head coupled to a distal portion of the endoscope, toform a piston pressure seal between the distal portion of the endoscopeand a wall of the colon when the endoscope is in the colon; and

advancing the piston head distally through the colon by applyingpressure to an external surface of the piston head.

There is additionally provided, in accordance with an embodiment of thepresent invention, a method including:

providing an endoscope shaped so as to define a channel therethrough,the endoscope having a piston head coupled to a distal portion thereof;

coupling the piston head to the channel, such that the channel is influid communication with an interior of the piston head;

inserting the endoscope into a colon;

inflating the piston head by applying pressure via the channel, to forma piston pressure seal between the distal portion of the endoscope and awall of the colon when the endoscope is in the colon;

advancing the piston head distally through the colon by applyingpressure to an external surface of the piston head; and

decoupling the piston head from the channel, while in the colon, afterthe piston head has been advanced through the colon.

There is yet additionally provided, in accordance with an embodiment ofthe present invention, a method including:

(a) inflating a mechanical device disposed in a colon of a patient;

(b) pulling a guiding element through the colon using the inflatedmechanical device;

(c) advancing a gastrointestinal tool along the guiding element; and

(d) repeating steps (b) and (c), until the gastrointestinal tool isadvanced to a desired site in the colon.

For some applications, inflating the mechanical device includes forminga first pressure seal between the mechanical device and a wall of thecolon, and pulling the guiding element includes advancing the mechanicaldevice distally through the colon by applying pressure to an externalsurface of the mechanical device.

For some applications, advancing the mechanical device includesfacilitating passage of fluid out of the colon from a site within thelumen distal to the mechanical device.

For some applications, applying the pressure to the external surface ofthe mechanical device includes inflating an annular balloon coupledaround a distal portion of the gastrointestinal tool, to form a secondpressure seal between the distal portion of the gastrointestinal tooland the wall of the colon.

In an embodiment, advancing the gastrointestinal tool includes:deflating the annular balloon; and after deflating the annular balloon,advancing the gastrointestinal tool, and pulling the guiding elementthrough the colon includes: inflating the annular balloon to form thesecond pressure seal; and after inflating the annular balloon, pullingthe guiding element through the colon using the inflated mechanicaldevice.

For some applications, advancing the gastrointestinal tool includesadvancing the gastrointestinal tool while maintaining the secondpressure seal.

There is also provided, in accordance with an embodiment of the presentinvention, a method including:

facilitating advancing of an endoscope through a colon by applying apressure via a channel of the endoscope; and

after the endoscope has been advanced to a desired site in the colon,using the channel to facilitate performance of a procedure.

For some applications, applying the pressure includes applying thepressure to inflate a piston head coupled to a distal portion of theendoscope.

For some applications, the method includes applying a pressure to anexternal surface of the piston head.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with theappended drawings in which:

FIG. 1 is a simplified illustration of a guiding element, in accordancewith an embodiment of the present invention, introduced through therectum into the large intestine all the way to the cecum;

FIG. 2 is a simplified illustration of an imaging device and sleeve slidover the guiding element of FIG. 1, in accordance with an embodiment ofthe present invention;

FIG. 3 is a simplified illustration of additional devices introducedover the guiding element of FIG. 1, such as, but not limited to, acatheter with a lumen for passing therethrough wires (electrical orother) and another lumen for introducing therethrough fluids, or othergastrointestinal tools and the like, in accordance with an embodiment ofthe present invention;

FIG. 4 is a simplified illustration of a gastrointestinal tool slid overthe guiding element of FIG. 1, in accordance with an embodiment of thepresent invention;

FIG. 5 is a simplified illustration of a gastrointestinal tool with apulley for movement over the guiding element of FIG. 1, in accordancewith an embodiment of the present invention;

FIG. 6 is a schematic illustration of a configuration of the guidingelement of FIG. 1, in accordance with an embodiment of the presentinvention;

FIG. 7 is a schematic cross-sectional view of a configuration of a boreof the guiding element of FIG. 6, in accordance with an embodiment ofthe present invention;

FIGS. 8A and 8B are schematic side and cross-sectional views,respectively, of a clip for use with a guiding element, in accordancewith an embodiment of the present invention; and

FIGS. 9 and 10 are schematic illustrations of respectivegastrointestinal systems, in accordance with respective embodiments ofthe present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to FIGS. 1 and 2, which illustrategastrointestinal apparatus 10, constructed and operative in accordancewith an embodiment of the present invention. Gastrointestinal apparatus10 may comprise a gastrointestinal tool 12 formed with a bore 14 thatadvances over a guiding element 16. Guiding element 16 passes throughbore 14. Examples of gastrointestinal tools 12 are describedhereinbelow. Guiding element 16 may be constructed of any suitableflexible, medically safe material, such as a plastic or metal.

In the following description, guiding element 16 is described as beingintroduced into the gastrointestinal tract, particularly the colon.However, it is emphasized that the invention is not limited to the GItract and may be used for any other body lumen.

As seen in FIG. 1, guiding element 16 may be introduced through a rectum18, past a sigmoid colon 20 and descending colon 22, where it may bendpast a splenic flexure 24, pass through a transverse colon 26, bend pasta hepatic flexure 28, pass into an ascending colon 30, and reach a cecum32, by any method.

Alternatively, guiding element 16 may be pulled through the colon, suchas by a self-propelled mechanical device (or other devices, such as butnot limited to, inflatable devices, electrical devices and the like).After guiding element 16 has been advanced through the colon,gastrointestinal tool 12 is then introduced into the colon along guidingelement 16. Gastrointestinal tool 12 may be shaped so as to define adistal chamfer 34, e.g., to facilitate movement distally into the colon.Alternatively or additionally, gastrointestinal tool 12 may be shaped soas to define a proximal chamfer 36, e.g., to facilitate extraction fromthe colon.

In an embodiment of the present invention, the mechanical devicecomprises a guide member at least partially insertable into the anus,and an inflatable piston head mounted in a vicinity of a distal end ofguiding element 16 (e.g., within several centimeters of a distal tip ofguiding element 16, or within 20 cm of the distal tip). The guide memberis: (a) shaped so as to define a first passageway connectable to asource of fluid pressure, and (b) configured to permit sliding movementof guiding element 16 through the guide member, while creating apressure seal between the guide member and the rectum. The source offluid pressure generates pressure in the colon proximal to the pistonhead, such that greater fluid pressure acting on a proximal side of thepiston head than on a distal side of the piston head propels the pistonhead and the guiding element in a distal direction in the colon.

For some applications, the fluid pressure source causes the pressureproximal to the piston head to vary slowly (e.g., less than 1 Hz). Forsome applications, a higher frequency variation of the pressure proximalto the piston head is applied (e.g., 1-10 Hz), as appropriate, in orderto maintain the desired motion of the colonoscope. In an embodiment, ahigher frequency variation (e.g., 1-10 Hz square or sinusoidal pressurepulses) is superimposed on a slow variation (e.g., a slow increase inpressure).

For some applications, a vent tube passes through the piston head. Thevent tube is shaped so as to define an opening distal to the piston headthrough which fluid is vented to the outside of the body. For someapplications, guiding element 16 is shaped so as to define a secondpassageway in fluid communication with the piston head, which passagewayis connected to a source of fluid pressure for inflating the pistonhead.

In an embodiment of the present invention, guiding element 16 is notinitially advanced the entire desired distance into the colon. Instead,the guiding element is advanced a smaller distance, e.g., 10 cm, andgastrointestinal tool 12 is advanced in the colon along the guidingelement by approximately the same distance. The guiding element and thetool are alternatingly advanced until the endoscope reaches a desiredlocation in the colon. For some applications, the guide member is notconfigured to create a pressure seal between the guide member and therectum (and, for some applications, the guide member is not provided).Instead, an annular balloon is placed around a distal region ofgastrointestinal tool 12 (e.g., within several centimeters of a distaltip of tool 12, or within 20 cm of the distal tip). While guidingelement 16 is being advanced, the annular balloon is in an inflatedstate that creates a pressure seal between the distal region of tool 12and the colon. After guiding element 16 has been advanced to a desiredintermediate location in the colon, the annular balloon is deflated soas to break the pressure seal. Tool 12 is then advanced along theguiding element, the annular balloon is reinflated, and the guidingelement is again advanced. This advancing technique results in thecreation of relatively high pressure in the colon at any given time onlybetween guiding element 16 and tool 12, rather than along the generallygreater distance between the guiding element and the guide member.

For some applications, techniques described in U.S. patent applicationSer. No. 10/967,922 to Cabiri et al., filed Oct. 18, 2004, entitled,“Pressure-propelled system for body lumen,” which is assigned to theassignee of the present application and is incorporated herein byreference, are used with the mechanical device, mutatis mutandis(including that the elongate carrier described therein comprises guidingelement 16 of the present application).

In an embodiment of the present invention, a pushing device 38, such asbut not limited to, a sleeve or catheter, is slid over guiding element16 to distally push gastrointestinal tool 12 over guiding element 16.For some applications, guiding element 16 comprises a distal stop 40that prevents distal movement of gastrointestinal tool 12 therepast. Forsome applications, distal stop 40 is inflatable, and is configured suchthat inflation of distal stop 40 fixes the position of guiding element16 in the colon.

Alternatively, for some applications, guiding element 16 does notcomprise distal stop 40. For some applications, after gastrointestinaltool 12 has been advanced along guiding element 16, the physicianremoves the guiding element from the colon. In embodiments in whichgastrointestinal tool 12 is shaped so as to define bore 14, removal ofguiding element 16 leaves the bore as a free working channel throughwhich additional tools or materials can be advanced or withdrawn.

In accordance with an embodiment of the present invention,gastrointestinal tool 12 may comprise an imaging device. The imagingdevice may comprise, without limitation, a CCD or CMOS camera, anillumination device, a vision device, an ultrasound sensor, and/or anx-ray emitter.

Reference is now made to FIG. 3, which is a simplified illustration ofdevices introduced over guiding element 16, in accordance with anembodiment of the present invention. For some applications,gastrointestinal tool 12 comprises a catheter 42 that slides overguiding element 16. Catheter 42 may comprise a lumen (also referred toas a channel) 44 for passing therethrough an instrument 46. Additionallyor alternatively, catheter 42 may comprise a lumen (also referred to asa channel) 48 for passing therethrough a fluid 50. Catheter 42 may berigid or flexible, and may have a one-piece or multiple-piececonstruction. Catheter 42 may comprise an inflatable, collapsiblesleeve, as is described hereinbelow.

Catheter 42 may include any number of lumens for multiple applications.Catheter 42 may be constructed of any suitable medically safe material,such as plastic or metal.

Catheter 42 may have a generally fixed form, or may be made of acollapsible material (e.g., nylon), such that after partial or completeintroduction into the body lumen, catheter 42 may be inflated tofunctionally create an endoscope with single or multiple channels thatrun through its length.

In accordance with another embodiment of the present invention,instrument 46 or gastrointestinal tool 12 comprises a cutting tool or asampling device for performing a variety of medical procedures, such as,but not limited to, removing polyps, performing sutures, irrigation,suction, and removing other tissues. Alternatively or additionally,gastrointestinal tool 12 may comprise a sensor for characterization oftissue, for example, for performing optical biopsy or chromoendoscopy(which relates to the spraying or injecting of a dye that isdifferentially accumulated by malignant tissue).

In accordance with an embodiment of the present invention,gastrointestinal tool 12 comprises a magnetic device, such as forcoupling with other GI devices. For example, the magnetic device may beused to magnetically attract magnetic boluses or other ingestibleobjects used for tracking or imaging the GI tract. Alternatively,gastrointestinal tool 12 comprises any other suitable attachment orattraction device, such as but not limited to, adhesives or fastenersfor attracting and affixing to such boluses or other ingestible objects.

In accordance with an embodiment of the present invention, substancesare introduced in the GI tract via gastrointestinal tool 12 and orguiding element 16. Such substances may include, without limitation,materials injected for image contrast or labeling, such as, but notlimited to, x-ray dyes, radioactivity-tagged materials orradiophalmaceuticals, magnetic resonance imaging (MRI) contrast agents,and others, or pharmaceuticals, relaxants, and other medicinalsubstances. Alternatively or additionally, a fluid (e.g., air) isintroduced in the GI tract via gastrointestinal tool 12 and or guidingelement 16 for inflating the colon. Such inflation of the colontypically enhances capturing images thereof, and/or enhances the localinjection of pharmaceutical compounds (e.g., only to the colon), such asfor the treatment of colitis and/or Crohn's disease.

In accordance with an embodiment of the present invention, guidingelement 16 is advanced to a vicinity of the furthest desired location ofgastrointestinal tool 12 in the colon (typically, to the cecum), and,subsequently, tool 12 is advanced along guiding element 16 to thevicinity of the desired location.

The present invention thus provides a unique way of constructinggastrointestinal apparatus by advancing gastrointestinal tool 12 along(e.g., over or alongside) guiding element 16. Subsequently other toolsmay be slid over guiding element 16 to cooperate with gastrointestinaltool 12. As mentioned before, a collapsible sleeve (e.g., which may takethe form of catheter 42 shown in FIG. 3) may be slid over guidingelement 16 and inflated to functionally create an endoscope with singleor multiple channels (e.g., 44 or 48) that run through its entire orpartial length.

Reference is now made to FIG. 4, which is a simplified schematicillustration of various gastrointestinal tools advanced along guidingelement 16, in accordance with an embodiment of the present invention.In the illustrated embodiment, an anchoring device 60 is provided toanchor guiding element 16 at any desired position in the GI tract. Theanchoring device 60 may be a balloon inflatable by means of pressurizedgas or liquid introduced through a lumen 62 in fluid communication withthe balloon. For some applications, guiding element 16 is anchored inorder to facilitate a treatment or diagnosis, and or to facilitatemovement of various components up and down the guiding element (e.g.,monorail), by preventing longitudinal force from dislodging the guidingelement (e.g., monorail) from its location. In an embodiment, anchoringdevice 60 comprises the inflatable piston head described hereinabove.

Different kinds of gastrointestinal tools may be slid over guidingelement 16, as mentioned hereinabove. Two examples of possibleconfigurations of such tools are shown in FIG. 4, in accordance withrespective embodiments of the present invention. In one configuration, agastrointestinal tool 64 comprises a coupling member 66 positionedinwards of the outer contour of gastrointestinal tool 64. Couplingmember 66 may be a sleeve or disc, for example, formed with a bore 68.Guiding element 16 passes through bore 68. In another configuration, agastrointestinal tool 70 comprises a coupling member 72 positionedoutside the outer contour of gastrointestinal tool 70. Coupling member72 may be an eyelet or small tube attached to the body of thegastrointestinal tool 70. Coupling member 72 may be formed with a bore74 through which guiding element 16 passes. In such a case, guidingelement 16 acts as a “monorail” with the gastrointestinal tool 70gliding along it like a cable car. In the second configuration, thegastrointestinal tool 70 may comprise a capsule or colonoscope, forexample.

There are many kinds of gastrointestinal tools that may be configured ineither of the two configurations just described. (The tools are shownschematically and simplistically in FIG. 4, and it is noted that theshape and size of the tools may not be as exactly shown in the figure.)Some non-limiting examples of such gastrointestinal tools include aradioactive device (e.g., a radioactive tube, radioactive needle,radioactive seed, and/or radioactive capsule or combination thereof), oran iontophoresis drug delivery device. The iontophoresis drug deliverydevice may comprise at least two electrodes in intimate electricalcontact with some portion of the GI tract, wherein one electrode is theactive or donor electrode, from which an ionic substance, agent,medicament, drug precursor or drug is delivered into the body via thewall of the GI tract by iontophoresis.

The other electrode, called the counter or return electrode, serves toclose the electrical circuit through the body. The circuit is completedby connection of the electrodes to a source of electrical energy, e.g.,a battery. One or both of the anode and the cathode may be used todeliver drugs of appropriate charge into the body.

Other non-limiting examples of such gastrointestinal tools include animaging device (e.g., miniature CCD or x-ray imaging device), aminiature injection device for injection of a substance (e.g., anendoscopically-actuated injection needle and/or syringe), a photodynamictherapy/diagnosis device (e.g., an LED-based light infusion device), ahyperthermic therapy/diagnosis device (e.g., miniature high frequencyultrashort wave electrodes), or an ultrasonic therapy/diagnosis device(e.g., miniature ultrasound transducer). The imaging or viewing devicemay be used to position the gastrointestinal tool at any desiredposition along guiding element 16.

In the case of diagnostic applications, energy, such as ultrasonic orx-ray energy, is applied to at least a portion of the GI tract to imagethe target tissue. A visible image of an internal region of the GI tractis then obtained, such that the presence or absence of diseased tissuecan be ascertained. With respect to ultrasound, ultrasonic imagingtechniques, including second harmonic imaging, and gated imaging, arewell known in the art. Ultrasound can be used for both diagnostic andtherapeutic purposes. In diagnostic ultrasound, ultrasound waves or atrain of pulses of ultrasound may be applied with a transducer. Theultrasound is generally pulsed rather than continuous, although it maybe continuous, if desired. Diagnostic ultrasound generally involves theapplication of a pulse of echoes, after which, during a listeningperiod, the ultrasound transducer receives reflected signals. Harmonics,ultraharmonics or subharmonics may be used. Energy levels fortherapeutic ultrasound may be used to perform hyperthermia.

Photodynamic therapy/diagnosis utilizes the administration of alight-sensitive drug, which is then exposed to a visible light beam,which, in the case of therapy, may destroy cancerous cells. It is knownthat certain dyes are accreted by lesions, such as tumors, which are inturn activated by a specific frequency of light. The photodynamictherapy/diagnosis device may employ laser-induced fluorescence to detectsites of cancer which have accreted the light-activated dye. Fluorescentand other chromagens, or dyes, such as porphyrins sensitive to visiblelight, have been used to detect and even treat lesions by directing thesuitable light to the tumor or lesion. Other synonymous names forphotodynamic therapy/diagnosis device include photoradiation andphototherapy.

Another gastrointestinal tool may include a dye applicator, which may beused to coat, paint, spray or otherwise apply a color, pigment, dye orother highlighting substance on the inner walls of the GI tract. In thismanner, polyps or other growths or anomalies may be highlighted so thatthey are more easily discerned and imaged by the colonoscope. This mayalso aid in pattern recognition of tissue in the colon by thecolonoscope, so as to facilitate analysis by the colonoscope. This mayalso enable placement of a landmark to facilitate returning thecolonoscope to the same location in the colon. It is also noted thatcertain polyps or other growths may react differently to the addition ofthe dye, such as in terms of color change, absorption, etc., and thereaction of the growth may be correlated to its probability of turninginto a cancerous growth. Optical biopsy techniques that may be usedinclude, but are not limited to, confocal microendoscopy, fluorescenceendoscopy, optical coherence tomography, light-scattering spectroscopy,Raman spectroscopy, and molecular imaging. For some applications,optical biopsy facilitates the performance of histological analysis oftissue of the colon.

A propulsion device 76 may be provided to propel (e.g., push or pull)the gastrointestinal tool along guiding element 16. For example, thepropulsion device 76 may include a push and/or pull wire attached to thetool. In another non-limiting example, the propulsion device 76 mayinclude a jet-propulsion device that moves the tool distally overguiding element 16 by means of a jet of water or air expelled proximallyfrom the jet-propulsion device. As another example, the propulsiondevice 76 may be a motor with gearing which may not need any externalconnections, which moves the gastrointestinal tool along guiding element16.

Reference is now made to FIG. 5, which illustrates a gastrointestinaltool 80 with another kind of propulsion device, in accordance with anembodiment of the present invention. In this embodiment, the propulsiondevice includes a pulley 82 for movement over guiding element 16. Agastrointestinal tool 84 may be coupled to pulley 82 and moved distallyand/or proximally along guiding element 16. The pulley 82 may beconnected to -the end of guiding element 16 or any other portionthereof, or to any other device that moves along or with the catheter(the catheter being guiding element 16).

Reference is now made to FIG. 6, which is a schematic illustration of aconfiguration of gastrointestinal device 10, in accordance with anembodiment of the present invention. In this configuration,gastrointestinal tool 12 is not formed with a bore, such as describedhereinabove with reference to FIGS. 1 and 2. Instead, tool 12 comprisesa coupling member 90, a tool-coupling portion 92 of which is typicallyfixed (i.e., non-slidably coupled) to tool 12. Coupling member 90 isshaped so as to define a bore 94 through a portion of the couplingmember, such that bore 94 is typically positioned adjacent to tool 12(e.g., laterally adjacent thereto). Guiding element 16 is configured topass through bore 94, such that tool 12 advances alongside guidingelement 16 without the guiding element passing through thegastrointestinal tool. For some applications, gastrointestinal device 10comprises a self-propelled mechanical device 96, for example asdescribed hereinabove and/or in the above-mentioned U.S. patentapplication Ser. No. 10/967,922 to Cabiri et al. For some applications,mechanical device 96 comprises a multi-lobed piston head, as shown inFIG. 6, similar to the configuration described with reference to FIGS.10A-11B of the Cabiri et al. application. Alternatively, for someapplications, mechanical device 96 comprises a single-lobed piston head(configuration not shown in FIG. 6).

FIG. 7 is a schematic cross-sectional view of a configuration of bore 94of coupling member 90, in accordance with an embodiment of the presentinvention. In this configuration, coupling member 90 comprises one ormore (e.g., two) wheels 100, typically coupled at first ends 102 thereofto tool-coupling portion 92. Wheels 100 are disposed so as to definebore 94 therebetween. In the configuration shown in FIG. 7, wheels 100are driven to rotate in opposite directions, in order to force guidingelement 16 to pass between the wheels, and thereby cause tool 12 toadvance along guiding element 16. As appropriate, wheels 100 may bedriven electrically, pneumatically, or hydraulically. For someapplications, coupling member 90 comprises a retaining element 104coupled to second ends 106 of wheels 100. Retaining element 104 preventsguiding element 16 from becoming disengaged from bore 94, and/ormaintains the wheels in alignment with each other. In an embodiment,guiding element 16 is flexible, has a diameter greater than about 4 mm(e.g., about 5.5 mm), and is slightly transiently deformed by pressureapplied thereto by wheels 100. For example, the guiding element maycomprise polyurethane.

FIGS. 8A and 8B are schematic side and cross-sectional views,respectively, of a clip 120, in accordance with an embodiment of thepresent invention. For some applications, gastrointestinal device 10comprises one or more clips 120, which serve to slidably couple guidingelement 16 to tool 12 along at least a longitudinal portion of theguiding element. Typically, a first portion 122 of clip 120 is fixed(i.e., non-slidably coupled) to tool 12, and a second portion 124 ofclip 120 is slidably coupled to guiding element 16. For someapplications, clip 120 comprises the wheel configuration describedhereinabove with reference to FIG. 7, but the wheels rotate passively.

Reference is now made to FIG. 9, which is a schematic illustration of agastrointestinal system 200, in accordance with an embodiment of thepresent invention. System 200 comprises an endoscope 210, such as aconventional colonoscope, which typically is shaped so as to define atleast one channel 212 therethrough. System 200 further comprises aguiding element 214, which is adapted to be pulled through the colon,such as by a mechanical device 216, e.g., an inflatable mechanicaldevice, an electrical mechanical device, and/or a self-propelledmechanical device. After guiding element 214 has been advanced throughthe colon, endoscope 210 is advanced in the colon along guiding element214.

For some applications, guiding element 214 is inserted into channel 212,such that as endoscope 210 advances, successive portions of the guidingelement are surrounded by the channel.

For other applications, a coupling member, similar to coupling member 72described hereinabove with reference to FIG. 4, is attached to endoscope210 (configuration not shown in FIG. 9). A portion of the couplingmember is positioned adjacent to the endoscope and defines a boretherethrough. As the endoscope advances, successive portions of theguiding element are surrounded by the bore. Alternatively, the couplingmember is integral to the body of the endoscope.

In an embodiment of the present invention, mechanical device 216comprises an inflatable piston head 220 mounted in a vicinity of adistal end of guiding element 214. Endoscope 210 is adapted to functionas a guide member at least partially insertable into a rectum 222. Aseparate guide member is thus typically not required in this embodiment.In order to create a pressure seal between a distal region 224 ofendoscope 210 and the rectum, an annular balloon 228 is placed aroundthe distal region of the endoscope (e.g., within several centimeters ofa distal tip of the endoscope, or within 20 cm of the distal tip). Theballoon is typically inflated by a positive pressure applied from afluid pressure source 230 through a tube 232.

Pressurized fluid (e.g., air) from a fluid pressure source 234 isintroduced into the colon through a first passageway 236. For someapplications, the first passageway passes around balloon 228, forexample between the balloon and the rectum (as shown in FIG. 9), throughthe balloon (configuration not shown), or between the balloon and theendoscope (configuration not shown). Alternatively, for someapplications, the first passageway is integral to the body of theendoscope, i.e., a channel of the endoscope functions as the firstpassageway (configuration not shown). Fluid pressure source 234generates pressure in the colon proximal to piston head 220, such thatgreater fluid pressure acting on a proximal side of the piston head thanon a distal side of the piston head propels the piston head and guidingelement 214 in a distal direction in the colon. For some applications, avent tube is provided that passes through piston head 220 (configurationnot shown). The vent tube facilitates passage of fluid out of the colonfrom a site distal to the piston head to the outside of the body. Forsome applications, guiding element 214 is shaped so as to define asecond passageway 238 in fluid communication with piston head 220, whichpassageway is connected to a source of fluid pressure 240 for inflatingthe piston head. In an embodiment, the pressure of pressure source 240and/or the pressure of pressure source 234 are actively regulated inorder to propel piston head 220.

After piston head 220 has been advanced through the colon, balloon 228is typically at least partially deflated, and endoscope 210 is advancedin the colon along guiding element 214, as described above.

In an embodiment of the present invention, guiding element 214 is notinitially advanced the entire desired distance into the colon. Instead,the guiding element is advanced a smaller distance, e.g., 10 cm, andendoscope 210 is advanced in the colon along the guiding element byapproximately the same distance. The guiding element and the endoscopeare alternatingly advanced until the endoscope reaches a desiredlocation in the colon.

For some applications in which mechanical device 216 comprises pistonhead 220, after each time guiding element 214 is advanced, balloon 228is deflated so as to break the pressure seal. Endoscope 210 is thenadvanced along the guiding element, the balloon is reinflated, and theguiding element is again advanced. This advancing technique results inthe creation of high pressure in the colon at any given time onlybetween guiding element 214 and endoscope 210, rather than along thegenerally greater distance between the guiding element and the balloonat the rectum. Alternatively, balloon 228 is configured to slide throughthe colon while maintaining a pressure seal with the wall of the colon,in which case the balloon need not be deflated as endoscope 210 isadvanced in the colon.

Reference is now made to FIG. 10, which is a schematic illustration of agastrointestinal system 250, in accordance with an embodiment of thepresent invention. System 250 typically comprises an endoscope 260, suchas a conventional colonoscope; a guide member 262 at least partiallyinsertable into a rectum 264; and an inflatable piston head 266 adaptedto be mounted in a vicinity of a distal end of endoscope 260. Guidemember 262 is: (a) shaped so as to define a first passageway 270connectable to a source of fluid pressure 272, and (b) configured topermit sliding movement of endoscope 260 through the guide member, whilecreating a pressure seal between the guide member and rectum 264. Fluidpressure source 272 generates pressure in the colon proximal to pistonhead 266, such that greater fluid pressure acting on a proximal side ofthe piston head than on a distal side of the piston head propels thepiston head and endoscope 260 in a distal direction in the colon.

For some applications, a vent tube 274 passes through piston head 266.The vent tube is shaped so as to define an opening 276 that opens to adistal region distal to piston head 266. Vent tube 274 vents fluid fromthe distal region to the outside of the body. For some applications,endoscope 260 is shaped so as to define a second passageway 278 in fluidcommunication with an interior of piston head 266, which passageway isconnected to a source of fluid pressure 280 for inflating the pistonhead.

For some applications, the techniques described herein are used incombination with techniques described in the above-mentioned U.S. patentapplication Ser. No. 10/967,922 to Cabiri et al., mutatis mutandis.

In an embodiment of the present invention, the gastrointestinal systemcomprises a conventional endoscope, such as described hereinabove withreference to some embodiments of FIGS. 9 and 10. In this embodiment, oneof the standard channels of the conventional endoscope functions as thesecond passageway (e.g., as second passageway 278 of FIG. 10) forinflating the piston head. For some applications, after the endoscopehas been advanced to the target site in the colon, the channel isdecoupled from the piston head. Such decoupling frees up the channel toperform one or more conventional endoscopic procedures, such as applyingpressure to inflate the colon distal to the endoscope, or transporting afluid or gas in or out of the colon. For example, one or more bursts ofhigh pressure may be applied to the channel in order to decouple it fromthe piston head.

For some applications, techniques described herein are used incombination with techniques described in one or more of the followingapplications, all of which are assigned to the assignee of the presentapplication and are incorporated herein by reference:

-   -   U.S. patent application Ser. No. 10/967,922 to Cabiri et al.,        filed Oct. 18, 2004, entitled, “Pressure-propelled system for        body lumen,”    -   U.S. patent application Ser. No. 10/838,648 to Gross et al.,        filed May 3, 2004, entitled, “Pressure-propelled system for body        lumen,”    -   U.S. patent application Ser. No. 10/753,424 to Gross et al.,        filed Jan. 9, 2004, entitled, “Pressure-propelled system for        body lumen,”    -   U.S. Provisional Patent Application 60/607,986 to Cabiri et al.,        filed Sep. 8, 2004, entitled, “Mechanical aspects of        pressure-propelled system for body lumen,” and    -   U.S. Provisional Patent Application 60/571,438 to Dotan et al.,        filed May 14, 2004, entitled, “Omnidirectional and        forward-looking imaging device.”

It is appreciated that various features of the invention which are, forclarity, described in the contexts of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

1. Gastrointestinal apparatus for use with a fluid pressure source, thegastrointestinal apparatus comprising: a guiding element, adapted to beinserted into a colon; a piston head coupled to a distal portion of theguiding element and adapted to: be inflated to form a first pressureseal between the piston head and a wall of the colon after the guidingelement has been inserted into the colon, and be advanced distallythrough the colon in response to pressure from the fluid pressure sourceapplied to an external surface of the piston head; a gastrointestinaltool adapted to be advanced along the guiding element; and an annularballoon coupled around a distal portion of the gastrointestinal tool,the balloon expandable to form a second pressure seal between the distalportion of the gastrointestinal tool and the wall of the colon.
 2. Theapparatus according to claim 1, wherein the gastrointestinal tool isadapted to be advanced along the guiding element when the annularballoon has been at least partially deflated.
 3. The apparatus accordingto claim 1, wherein the gastrointestinal tool is shaped so as to definea channel therethrough, and wherein the guiding element is shaped topass through the channel.
 4. The apparatus according to claim 1, whereinthe gastrointestinal tool comprises a coupling member shaped so as todefine a bore therethrough, and wherein the guiding element isconfigured to pass through the bore and not to pass through thegastrointestinal tool.
 5. The apparatus according to claim 1, comprisinga passageway having proximal and distal ends, the proximal end coupledto the fluid pressure source, and the distal end open to a site betweenthe external surface of the piston head and the annular balloon.
 6. Theapparatus according to claim 1, wherein the gastrointestinal tool isshaped so as to define a passageway therethrough having proximal anddistal ends, the proximal end coupled to the fluid pressure source, andthe distal end open to a site between the external surface of the pistonhead and the balloon.
 7. The apparatus according to claim 1, comprisinga vent tube, adapted to facilitate passage of fluid out of the colonfrom a site distal to the piston head.
 8. Gastrointestinal apparatus foruse with an endoscope shaped so as to define a channel therethrough, thegastrointestinal apparatus comprising: a fluid pressure source; and apiston head adapted to be coupled to a distal portion of the endoscope,the piston head adapted to: be inflated so as to form a piston pressureseal between the distal portion of the endoscope and a wall of a colonwhen the endoscope is in the colon, and be advanced distally through thecolon in response to pressure from the fluid pressure source applied toan external surface of the piston head.
 9. The apparatus according toclaim 8, comprising a guide member, adapted to: be at least partiallyinsertable into a rectum, permit sliding movement of the endoscopethrough the guide member, and create a rectal pressure seal between theguide member and the rectum.
 10. The apparatus according to claim 8,comprising a second fluid pressure source, in fluid communication withan interior of the piston head via the channel.
 11. The apparatusaccording to claim 8, comprising a vent tube, adapted to facilitatepassage of fluid out of the colon from a site distal to the piston head.12-15. (canceled)
 16. A method comprising: inserting a guiding elementinto a colon; inflating a piston head coupled to a distal portion of theguiding element, to form a first pressure seal between the piston headand a wall of the colon after the guiding element has been inserted intothe colon; inflating an annular balloon coupled around a distal portionof a gastrointestinal tool, to form a second pressure seal between thedistal portion of the gastrointestinal tool and the wall of the colon;advancing the guiding element distally through the colon by applyingpressure to an external surface of the piston head; and advancing thegastrointestinal tool along the guiding element.
 17. The methodaccording to claim 16, wherein advancing the gastrointestinal tool alongthe guiding element comprises at least partially deflating the annularballoon, and advancing the gastrointestinal tool along the guidingelement while the annular balloon is at least partially deflated. 18.The method according to claim 16, wherein advancing the gastrointestinaltool along the guiding element comprises passing the guiding elementthrough a channel defined in the gastrointestinal tool.
 19. The methodaccording to claim 16, wherein advancing the gastrointestinal tool alongthe guiding element comprises passing the guiding element through a boredefined in a coupling member coupled to the tool, and not passing theguiding element through the gastrointestinal tool.
 20. The methodaccording to claim 16, wherein applying the pressure comprises applyingthe pressure via a passageway having proximal and distal ends, theproximal end coupled to a fluid pressure source, and the distal end opento a site between the external surface of the piston head and theannular balloon.
 21. The method according to claim 16, wherein applyingthe pressure comprises applying the pressure via a passageway defined inthe gastrointestinal tool, the passageway having proximal and distalends, the proximal end coupled to a fluid pressure source, and thedistal end open to a site between the external surface of the pistonhead and the balloon.
 22. The method according to claim 16, whereinadvancing the guiding element comprises facilitating passage of fluidout of the colon from a site distal to the piston head.
 23. The methodaccording to claim 16, wherein advancing the guiding element andadvancing the gastrointestinal tool along the guiding element comprisealternatingly advancing the guiding element and the gastrointestinaltool along the guiding element until the gastrointestinal tool isadvanced to a desired site in the colon.
 24. A method comprising:inserting, into a colon, an endoscope shaped so as to define a channeltherethrough; inflating a piston head coupled to a distal portion of theendoscope, to form a piston pressure seal between the distal portion ofthe endoscope and a wall of the colon when the endoscope is in thecolon; and advancing the piston head distally through the colon byapplying pressure to an external surface of the piston head.
 25. Themethod according to claim 24, comprising: at least partially inserting aguide member into a rectum; sliding the endoscope through the guidemember; and creating a rectal pressure seal between the guide member andthe rectum.
 26. The method according to claim 24, wherein inflating thepiston head comprises applying pressure to an interior of the pistonhead via the channel.
 27. The method according to claim 24, whereinadvancing the piston head comprises facilitating passage of fluid out ofthe colon from a site distal to the piston head. 28-31. (canceled)
 32. Amethod comprising: (a) inflating a mechanical device disposed in a colonof a patient; (b) pulling a guiding element through the colon using theinflated mechanical device; (c) advancing a gastrointestinal tool alongthe guiding element; and (d) repeating steps (b) and (c), until thegastrointestinal tool is advanced to a desired site in the colon. 33.The method according to claim 32, wherein inflating the mechanicaldevice comprises forming a first pressure seal between the mechanicaldevice and a wall of the colon, and wherein pulling the guiding elementcomprises advancing the mechanical device distally through the colon byapplying pressure to an external surface of the mechanical device. 34.The method according to claim 33, wherein advancing the mechanicaldevice comprises facilitating passage of fluid out of the colon from asite within the lumen distal to the mechanical device.
 35. The methodaccording to claim 33, wherein applying the pressure to the externalsurface of the mechanical device comprises inflating an annular ballooncoupled around a distal portion of the gastrointestinal tool, to form asecond pressure seal between the distal portion of the gastrointestinaltool and the wall of the colon,
 36. The method according to claim 35,wherein advancing the gastrointestinal tool comprises: deflating theannular balloon; and after deflating the annular balloon, advancing thegastrointestinal tool, and wherein pulling the guiding element throughthe colon comprises: inflating the annular balloon to form the secondpressure seal; and after inflating the annular balloon, pulling theguiding element through the colon using the inflated mechanical device.37. The method according to claim 35, wherein advancing thegastrointestinal tool comprises advancing the gastrointestinal toolwhile maintaining the second pressure seal.
 38. A method comprising:facilitating advancing of an endoscope through a colon by applying apressure via a channel of the endoscope; and after the endoscope hasbeen advanced to a desired site in the colon, using the channel tofacilitate performance of a procedure.
 39. The method according to claim38, wherein applying the pressure comprises applying the pressure toinflate a piston head coupled to a distal portion of the endoscope. 40.The method according to claim 39, and comprising applying a pressure toan external surface of the piston head.